Clinical Practice Guideline Update by the Infectious Diseases Society of America on Group A Streptococcal (GAS) Pharyngitis

Update History

This is Part 1 of an update to the 2012 IDSA Guideline on Diagnosis and Management of Group A Streptococcal Pharyngitis.

Background 

A sore throat, or pharyngitis, is among the most common reasons for seeking care in the outpatient setting for both adults and children. Symptoms such as fever, cough, rhinorrhea, and lymphadenopathy may also be present. Most episodes of pharyngitis are caused by viruses and resolve without specific therapy. However, pharyngitis is among the most common syndromes prompting outpatient antimicrobial therapy,¹ in part because it is difficult to distinguish viral infections from bacterial infections clinically.     

Streptococcus pyogenes is the etiology of pharyngitis in up to 15% of adults and 30% of children with pharyngitis.² In this guideline we will refer to S. pyogenes as group A Streptococcus (GAS), though in rare circumstances, group A antigen may be expressed by other streptococci such as the anginosus group and S. dysgalactiae subspecies equisimilis, which are members of the upper airway flora, but which are not commonly associated with pharyngitis. GAS is important to identify and treat in order to decrease the risks of nonsuppurative and suppurative sequelae that can be severe. However, the literature assessing the degree of effect of antibiotic treatment in preventing these sequelae is primarily from studies that were performed before the modern era of randomized clinical trials, and the relevance of their conclusions to current practice may be limited by their having included less rigorous diagnostic testing, more common use of parenteral antibiotics rather than oral antibiotics, and different prevalence of strains associated with sequelae such as rheumatic fever.^3,4 Other benefits of treatment include economic and societal benefits in decreasing the number of days of missed school and work due to GAS.    

On the other hand, overdiagnosis and overtreatment of GAS are associated with downsides that include financial cost as well as the adverse effects of unnecessary antibiotics for both individual patients and the public, including the impact of antibiotic use on the rates of antimicrobial resistance.     

Among the challenges in the assessment and management of patients presenting with sore throat are the difficulty in clinically identifying which patients may have pharyngitis due to GAS infection and should undergo diagnostic testing and the uncertainties about which test(s) are most helpful; what treatment and what treatment duration are appropriate, including for patients who are penicillin-allergic; the role of post-treatment testing; and consideration of the syndrome of GAS carriage or colonization.   

Here we include recommendations on risk assessment for GAS using clinical scoring systems in children and adults. Subsequent updates will address these other areas of uncertainty.  

Methods

The panel included clinicians with expertise in infectious diseases, pediatrics, public health, microbiology, family medicine, internal medicine and pharmacy. The following organizations reviewed and provided feedback on the associated manuscript: American Academy of Family Physicians (AAFP), Pediatric Infectious Diseases Society (PIDS), American Academy of Pediatrics (AAP), American Society for Microbiology (ASM), and Society of Infectious Diseases Pharmacists (SIDP). 

 A systematic review was performed to identify relevant studies, and the GRADE (Grading of Recommendations Assessment, Development and Evaluation) approach was followed for assessing the certainty of evidence and strength of recommendation (Figure 1).  

Details of the systematic review and guideline development processes are available in the supplemental materials for the included manuscript. 

Figure 1. Approach and implications to rating the quality of evidence and strength of recommendations using GRADE methodology (unrestricted use of figure granted by the U.S. GRADE Network) 

Recommendation: Risk Assessment Using Clinical Scoring Systems in Children and Adults

This recomendation is endorsed by the American Society of Microbiology and the Society of Infectious Diseases Pharmacists

Section last reviewed and updated on 10/14/2025

Last literature search conducted March 2025

[View full manuscript here]

[View supplemental material here]

In children and adults with sore throat, should a clinical scoring system be used to determine who should be tested for GAS? 

Recommendation

In children and adults with sore throat, we suggest using a clinical scoring system to determine who should be tested for GAS (conditional recommendation, very low certainty of evidence)  

Remarks 

1. High-risk individuals should be strongly considered for testing even if their clinical scores are low. Examples of high-risk individuals include those presenting with sore throat who have had household exposure to GAS (e.g., living or sleeping in the same indoor shared space as a person diagnosed with GAS infection), a history of a previous rheumatic fever diagnosis, or symptoms or signs suggestive of complicated local or systemic GAS infection (e.g., peritonsillar or retropharyngeal abscess, scarlet fever and/or toxic shock syndrome). 
2. The panel recommends that a clinical scoring system be used as part of the evaluation of patients with sore throat. The principal utility of a scoring system is to identify patients with low probability of GAS pharyngitis, in whom further evaluation by diagnostic testing is unlikely to be helpful.  
3. Given the lack of evidence favoring any particular scoring system, clinicians and patients may favor clinical scoring systems that do not include laboratory test(s).   
4. The recommendation to use a scoring system does not apply to children under three years of age as GAS infection in this age group may not present with typical clinical features represented in these scoring systems.⁵ 

A strong recommendation means most informed people would choose the recommended course of action and only a small proportion would not.    

A conditional recommendation means the majority of informed people would choose the suggested course of action, but many would not. 

Results

A systematic search identified six observational studies that met the inclusion criteria and compared use of a clinical scoring system to clinician judgement alone to determine which patients with sore throat should be tested for GAS.^6-11 All studies used throat culture as the reference standard. The scoring systems evaluated include those described by Breese, McIsaac, Centor, Attia, and Fujikawa.^6,7,9,12 One study reported data for combined pediatric and adult populations, as well as separately for each group.¹⁰ Four studies focused exclusively on children^6,8,9,11 and one study focused on adults.⁷   

Table 1. Summary of Findings per Outcome for Studies Comparing Use of Clinical Scoring System vs. No Scoring System in Evaluation of Patients with Suspected GAS Pharyngitis  

Rationale for recommendations

Existing studies directly comparing the outcome of using a clinical scoring system versus usual clinical practice without a scoring system have limitations: small sample size, lack of uniformity in outcome measures, incomplete data, and not being contemporary. Evidence from studies in children and adults suggest diagnostic accuracy is comparable or slightly higher with the use of a scoring system as compared to clinician judgement alone. In addition, the derivation and validation studies of the Centor^7,13 and McIsaac^10,14 criteria, and particularly the large validation study of both systems by Fine et al¹⁵ provide robust estimates of the probability of a positive rapid test or throat culture for GAS associated with all possible scores of the Centor or McIsaac scoring systems.  

The panel recommends that a clinical scoring system be used to identify patients with low probability of GAS pharyngitis, in whom further evaluation by diagnostic testing is unlikely to be helpful (e.g., a high risk of false positive testing in a low probability patient) or change clinical management. Use of a clinical scoring system can assist the clinician by providing a quantitative estimate of the probability of a positive throat culture in an individual patient. Such estimates can be a valuable part of clinical decision-making regarding the need for further testing by RADT, NAAT, or throat culture, together with consideration of individual risk factors, local epidemiology, costs of testing and treatment, and patient and family preferences.^16-18  

While studies have not addressed the impact of scoring systems on health care equity, the use of a scoring system may be expected to decrease risks of implicit or other biases by encouraging consistent and standardized decision-making regarding testing for GAS. Minimal direct harm is anticipated from implementing such a system. Implementation costs are expected to be low. The consensus of the panel is that the balance of benefits and harms favors implementation of a clinical scoring system as part of the evaluation of patients with sore throat.  

The following table (Table 2) lists examples of clinical scoring systems and their associated criteria that clinicians could consider using to help predict the likelihood of pharyngitis due to GAS.  

References  

1. Fleming-Dutra KE, Hersh AL, Shapiro DJ, et al. Prevalence of inappropriate antibiotic prescriptions among US ambulatory care visits, 2010–2011. JAMA. 2016;315(17):1864-1873. doi:10.1001/jama.2016.4151
2.  Pelucchi C, Grigoryan L, Galeone C, Esposito S, Huovinen P, et al. Guideline for management of acute sore throat. Clin Microbiol Infect. 2012;18(Suppl 1):1-28. doi:10.1111/j.1469-0691.2012.03766.x 
3. Zwart S, Rovers MM, de Melker RA, Hoes AW. Penicillin for acute sore throat in children: randomised, double blind trial. BMJ. 2003;327:1324-1330. doi:10.1136/bmj.327.7427.1324 
4. Spinks A, Glasziou PP, Del Mar CB. Antibiotics for treatment of sore throat in children and adults. Cochrane Database Syst Rev. 2021;12:CD000023. doi:10.1002/14651858.CD000023.pub5 
5. Woods WA, Carter CT, Schlager TA. Detection of group A streptococci in children under 3 years of age with pharyngitis. Pediatr Emerg Care. 1999;15(5):338-340. doi:10.1097/00006565-199910000-00011 
6. Breese BB. A simple scorecard for the tentative diagnosis of streptococcal pharyngitis. Am J Dis Child. 1977;131:514-517. 
7. Centor RM, Witherspoon JM, Dalton HP, et al. The diagnosis of strep throat in adults in the emergency room. Med Decis Making. 1981;1:239-246. 
8. Funamura JL, Berkowitz CD. Applicability of a scoring system in the diagnosis of streptococcal pharyngitis. Clin Pediatr. 1983;22:622-626. 
9. Fujikawa S, Ito Y, Ohkuni M. A new scoring system for diagnosis of streptopharyngitis. Jpn Circ J. 1985;49:1258-1261. 
10. McIsaac WJ, White D, Tannenbaum D, et al. A clinical score to reduce unnecessary antibiotic use in patients with sore throat. CMAJ. 1998;158:75-83.
11.  Attia MW, Zaoutis T, Klein JD, et al. Performance of a predictive model for streptococcal pharyngitis in children. Arch Pediatr Adolesc Med. 2001;155:687-691. 
12. Attia M, Zaoutis T, Eppes S, et al. Multivariate predictive models for group A beta-hemolytic streptococcal pharyngitis in children. Acad Emerg Med. 1999;6:8-13. 
13. Wigton RS, Connor JL, Centor RM. Transportability of a decision rule for the diagnosis of streptococcal pharyngitis. Arch Intern Med. 1986;146(1):81-83. 
14. McIsaac WJ, Goel V, To T, Low DE. The validity of a sore throat score in family practice. CMAJ. 2000;163:811-815. 
15. Fine AM, Nizet V, Mandl KD. Large-scale validation of the Centor and McIsaac scores to predict group A streptococcal pharyngitis. Arch Intern Med. 2012;172(11):847-852. 
16. Daniels R, El Omda T, Mokbel K. Improving antimicrobial stewardship in acute sore throat: Comparison of FeverPAIN and McIsaac scores with molecular point of care testing using Abbott ID NOW. Diagnostics (Basel). 2024;14(23):2680. doi:10.3390/diagnostics14232680 
17. Gunnarsson RK, Ebell M, Centor R, et al. Best management of patients with an acute sore throat: A critical analysis of current evidence and a consensus of experts from different countries and traditions. Infect Dis (Lond). 2023;384-395. doi:10.1080/23744235.2023.2191714 
18. Gunnarsson R, Orda U, Elliott B, Heal C, Del Mar C. What is the optimal strategy for managing primary care patients with an uncomplicated acute sore throat? Comparing the consequences of nine different strategies using a compilation of previous studies. BMJ Open. 2022;12(4):e059069. doi:10.1136/bmjopen-2021-059069
19.  Hamilton W, McCrea C. Streptococcal Pharyngitis: Rapid Evidence Review. Am Fam Physician. 2024;109(4):343-349. 

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